interface Com {
    int add(int a,int b);
}
abstract class A1 {
    abstract int add(int a,int b);
}
class B1 extends A1 implements Com {
    public int add(int a,int b) {
        return a+b;
    }
}
public class E6_2 {
public static void main(String args[]) {
    B b = new B();
    Com com = b;
    System.out.println(com.add(12,6));
    A a = b;
    System.out.println(a.add(10,5));
}
}
